Self-positioning baffle for shell and tube heat exchangers

ABSTRACT

A shell and tube heat exchanger including a plurality of transverse baffle plates which may be made of a resilient formable organic compound, the baffle plate adapted to be disposed within the shell and includes positioning means associated with the baffle plate axially projecting from at least one side thereof adapted to matingly engage an axially adjacent baffle plate such that adjacent baffle plates are spaced in a relatively fixed position both axially and rotationally with respect to each other and a method for making same.

United States Patent Donaldson [45] Apr. 1, 1972 [54] SELF-POSITIONINGBAFFLE FOR 2,498,145 2/1950 Tinker SHELL AND TUBE HEAT 2,855,206 10/1958Haviland...

1,904,875 4/1933 Metzgar EXCHANGERS 2,608,387 8/1952 Randall ..257/44[72] Inventor: Desmond M. Donaldson, Oakville, On-

tario, Canada Primary Examiner-Charles Sukalo Assistant Examiner-W. C.Anderson Asslgl'leel Corporation Chlcago, AttorneyDona1d W. Banner,William S. McCurry and John 221 Filed: Apr. 23, 1970 Bulchel [211 App].No.: 31,338 [57] ABSTRACT A shell and tube heat exchanger including aplurality of trans- [52] U.S. Cl ..165/159 verse baffle plates which maybe made of a resilient formable [51] lnt.Cl organic compound, the baffleplate adapted to be disposed [58] Field of Search ..165/159, 161;122/510; within the shell and inc udes positioning means associated 1 ogg A 9 R, 93; 29/1573 with the baffle plate axially projecting from atleast one side thereof adapted to matingly engage an axially adjacentbaffle [56] References Cited plate such that adjacent baffle plates arespaced in a relatively fixed position both axially and rotationally withrespect to UNITED STATES PATENTS each other and a method for makingsame.

3,400,758 9/1968 Man Suk Lee ..165/159 26 Claims, 12 Drawing FiguresPAIENTEMPR 18 I972 sum 10!: 2

SELF-POSITIONING BAFFLE FOR SHELL AND TUBE HEAT EXCHANGERS BACKGROUND OFTHE INVENTION This invention relates to heat exchangers of the shell andtube type and more specifically, to a heat exchanger incorporating aself-positioning baffle plate.

Baffle plates are used in shell and tube heat exchangers for two primaryreasons:

a. as a support for heat exchange tubes which extend through the lengthof the heat exchangers, and

b. as a means for directing a heat exchange fluid to follow a tortuouspath across the tubes to obtain maximum heat exchange exposure.

During construction of the heat exchanger, it is necessary to axiallyspace or position the baffle plates along the length of the heatexchanger to achieve both the desired support and flow path. A varietyof methods have been employed to so space or position these baffles.

A commonly employed method is to use a baffle in which the tube hole isa relatively tight fit on the tube. Thus, after inserting the tubesthrough the tube holes there is considerable friction between baffle andtubes which may be enough to hold the baffle in place. Unfortunately,sometimes, through vibration, the baffle may become loose and slip outof position or alternatively, cut through the tube.

An alternate method is to solder, braze or weld the baffles to thetubes. A disadvantage of this method is that the heat of soldering,brazing or welding anneals and thus weakens the tubes.

Separate mechanical means are quite frequently employed. These consistsometimes of longitudinal bars or rods onto which the baffles arethreaded, with intermediate sections of tubes to keep the bafflesproperly spaced. In another separate mechanical method, notched orslotted longitudinal bars are fitted over the baffles at their outerperiphery. The engagement of the baffles and the notches keeps them inplace. These two methods are disclosed in U.S. Pat. Nos. 2,873,098 and3,240,267.

Another method of positioning the baffles with respect to each other andthe shell is to constrict the outer shell locally, so as to hold orrestrict the battle from axial movement. Various means of this type aredescribed in U.S. Pat. Nos. 1,794,336, 2,978,226 and 3,240,267.

The present invention is an improvement over all the prior art methodsdiscussed in that it provides a baffle which has incorporated, either asan integral part or as a preassembled attachment, positioning meansprojecting from one or both sides designed to keep the series of bafflesand their headers properly oriented in their designated positions.

The present invention further provides baffles incorporating positioningmeans which include means of interlocking with other baflles so that aseries of baffles may be preassembled into a tube cage or framework intowhich the tubes may be in serted, thus greatly simplifying the assemblyprocedure. Such an arrangement provides accurate, reliable and simplemeans of initially positioning all of the baffles both axially androtationally with respect to each other and ensures that during theprocess of assembling the tubes to the heat exchanger, the baffles willremain properly positioned. It further ensures that during the life ofthe heat exchanger, the baffles will be held 6 BRIEF DESCRIPTION OF THEDRAWINGS FIG. 1 is a central longitudinal section of a heat exchangerincorporating the principles of the present invention.

FIG. 2 is a plan view of one of the heat exchanger baffles.

FIG. 3 is a side viewof the bafile shown in FIG. 2.

FIG. 4 is a detailed cross-section to a somewhat enlarged scale on theline 4-4 of FIG. 2.

FIG. 5 is a detailed cross-section to a somewhat enlarged scale on theline 5-5 of FIG. 2.

HG. 6 is a detailed cross-section to a somewhat enlarged scale on theline 6-6 of FIG. 2.

FIG. 7 is'a detailed cross-section in an enlarged scale on the line 7--7of FIG. 3.

FIG. 8 is a detailed cross-section in an enlarged scale on the line 8-8of FIG. 3.

FIG. 9 is a perspective view of an alternative embodiment of a baffleincorporating the features of the present invention.

FIG. 10 is a side view showing one modified construction of the bafileplate.

FIG. 11 is a side view showing another modified construction of thebafile plate.

FIG. 12 is a side view showing still another modification of the baffleplate.

Referring now to FIG. 1, there is shown a heat exchanger generallyidentified as 10. The heat exchanger includes a pair of headers 11 and12, a pair of tube plates 15 and 16, each connected to a header, and ashell 17 connected between the tube plates 15 and 16. A fluid inlet 20is defined in the tube plate 16 for a first heat exchange fluid. Conduitmeans 21 are connected to the fluid inlet. A fluid outlet 22 is definedin the tube plate 15 for the first heat exchange fluid. Conduit means 25are connected to the fluid outlet 22. A fluid inlet 26 is defined in theheader 12 for a second heat exchange fluid. A fluid outlet 27 is definedin the header 12 for the second heat exchange fluid. An inlet chamber 30is defined by the header 12 adjacent the fluid inlet 26. An outletchamber 31 is defined by the header 12 adjacent the outlet 27. Theheader 12 is provided with a central diametrical partition 32 whichseparates the inlet chamber 30 from the outlet chamber 31. A fluidchamber 33 is defined by the header 11.

A plurality of parallel heat exchange tubes 34 and 35 are provided inany suitable number and arrangement in accordance with standard practiceand extend between the tube plates 15 and 16, their end portionsextending through a series of openings 36 defined by the tube plates.The tubes 34 are in communication with the inlet chamber 30 and thetubes 35 are in communication with the outlet chamber 31. Both sets oftubes 34 and 35 are in communication with the fluid chamber 33. Thetubes are sealed to the tube plates in any of a number of standardmanners, such as by brazing.

The tubes are supported between the tube plates 15 and 16 by a series ofbaffles 37. As best illustrated in FIG. 2, each of the bafiles 37comprises a generally circular piece having a chordal segment removedfrom one side to afford a passage for the first heat exchange fluid. Thebaffles are arranged alternately in spaced relation with the removedsegment of alternate baffles on opposite sides of the heat exchangershell 17 to provide a tortuous path, as shown by the arrows in FIG. 1,for a first heat exchange fluid from the inlet 20 at one end of theshell to the outlet 22 at the other end of the shell. The baffles areprovided with a plurality of apertures 40 through 5 which are insertedthe heat exchange tubes 34 and 35.

As best seen in FIG. 3, the baffle comprises a plate member 41 havingaxially opposed front and rear surfaces 42 and 45 respectively.Positioning means, generally referred to as 46, are shown connected tothe plate member 41 and projecting from at least one side of said frontor rear surfaces of said plate.

FIG. 2 shows a first group of positioning means 47 positioned around theperiphery of the baffle 37 and a second group of positioning means 50positioned inwardly of the periphery. Details of the positioning means47 are best shown in FIGS. 4 and 5 and details of positioning means 50are best shown in FIG. 6.

The positioning means 46, shown in FIG. 3, project from both front 42and rear 45 surfaces of the plate member 41 and include a first end 51axially extending from the rear surface 45 of the plate 41. The firstend 51 includes an axially extending male connector 52. The connector 52includes a cylindrical portion 55, a tapered end 56 connected to thecylindrical portion 55, and an annular ring 57 positioned on thecylindrical portion 55 and of greater diameter than the cylindricalportion. The positioning means 46 also includes a second end 60 axiallyextending from the front surface 42 of the plate member 41. The secondend 60 defines an axially inwardly extending socket connection 61. Thesocket connection 61 includes a generally cylindrical portion 62 and anannular groove 65 of greater diameter than the cylindrical portion 62.The socket connection 61 is adapted to matingly receive a male connector52 of an adjacent baffle plate.

The male connector 52 and the socket connection 61 are designed suchthat when the male connector is inserted into the socket connection, theannular ring 57 deforms slightly upon entering the cylindrical portion62 and upon further insertion is allowed to expand into the annulargroove 65.

Such an arrangement assures a positive connection between adjacentbaffle plates which can only be separated upon exerting a separationforce of a higher magnitude than would normally be encountered in theoperation of such a heat exchanger. Such a connection serves to positionbaffle plates both axially and rotationally with respect to adjacentbaffle plates and to restrain relative axial and rotational movementbetween these baffle plates. The positioning means 46 may be either anintegral part of the baffle plate or a preassembled attachment. Eitherthe baffle plate or the positioning means or both may be made of aresilient formable organic compound. The compounds that have been foundsuitable for use in this capacity have been such materials as treatednylon (polyamides) and the high temperature polyesters such as polyarylether, however, other thermoplastic materials would be equally useful.

FIG. 9 shows a modified form of baffle plate including positioning means66 axially extending from a front surface 67 of a baffle plate 70 anddefining axially extending male connections 71. Other positioning means72 are connected to the baffle plate 70 and extending from the frontsurface 67 in the same direction as the positioning means 66. Thepositioning means 72 define axially inwardly extending socketconnections 75. A similar arrangement of positioning means 76 and 77 areshown extending from a rear surface 80 of the baffle plate 70. Thepositioning means 76 define socket connections and the positioning means77 define male connectors.

FIG. shows an alternative embodiment of a baffle which includes a baffleplate 81 of corrugated cross-section. Such a construction is felt to bestronger than baffle plates formed in a single plane. The baffle 81includes positioning means 82 and 85 of the type previously described.

FIG. 11 shows an alternative embodiment of a baflle plate 86 whichincludes stiffening ribs 87 connected to the baffle plate to addrigidity.

FIG. 12 discloses an alternative embodiment of a baffle plate assemblywhich includes extensions 90 which are adapted to each end to matinglyengage the positioning means 91 of adjacent baffles 92 and 95 and serveto space the baffles axially further apart than the positioning meanswould allow.

The operation of the shell and tube heat exchanger 10, as shown in FIG.1, is as follows. The second heat exchange fluid is communicated to thefluid inlet 26 and flows to the inlet chamber 30 where it iscommunicated to all of the various heat exchange tubes 34 incommunication with the chamber 30. The fluid travels through the tubes34 into the fluid chamber 33. Fluid passes from the fluid chamber 33into a second set of heat exchange tubes 35 through which the fluidflows to fluid chamber 31. Fluid flows from the chamber 31 to the fluidoutlet 27. The first heat exchange fluid flows from conduit 21 throughfluid inlet 20. The fluid then follows a tortuous path around the baflleplates, as shown by the arrows in FIG. 1, in heat exchange relationshipwith the tubes 34 and 35. The tortuous path through which the first heatexchange fluid flows operates to maximize the heat exchange efficiencyof this device. The second heat exchange fluid is exhausted from theheat exchanger 10 through fluid outlet 22 and conduit 25.

A preferred method of assembling such a heat exchanger which employs theself-positioning bafi'les previously described comprises assembling anelement of the heat exchanger first by forming a tube cage by connectinga plurality of bafile plates one to another by connecting thepositioning means of adjacent baffle plates such that the apertures ofeach baffle plate are substantially axially aligned and such that thebaffles are alternately arranged to provide a tortuous path for a firstheat exchange fluid; inserting a plurality of heat exchange tubesaxially through the tube cage; inserting the assembled tube cage into ashell member; positioning a tube plate at each end of the tube cage andaligning the apertures in the tube plate with the heat exchange tubes;sealing the tubes to the tube plates; and sealing the tube plates to theshell. The headers are then attached to the element by sealing theheaders to the tube plates.

Thus it has been shown that a shell and tube heat exchanger has beenprovided which includes a plurality of transverse baffle plates disposedwithin the shell which baffle plates include positioning means adaptedto engage adjacent baffle plates and to position both axially androtationally, each baffle plate with respect to its adjacent baffleplates. Further, a baffle plate has been shown which may be made of aresilient formable organic compound. Further, a method of assemblingsuch a heat exchanger has been disclosed which provides an accurate,reliable and economical means of assembling such a heat exchanger.

While this invention has been described in connection with certainspecific embodiments thereof, it is to be understood that this is by wayof illustration and not by way of limitation and the scope of thisinvention is defined solely by the appended claims which should beconstrued as broadly as the prior art will permit.

What is clairned is:

1. A baffle for a shell and tube heat exchanger having tubes and ahollow shell, said baffle adapted to be disposed in said shell andcomprising a plate member having axially opposed front and rear surfacesand defining a plurality of apertures; positioning means formed as anintegral part of said plate member and projecting from at least one ofsaid front or rear surfaces of said plate member, said positioning meanshaving at least one end adapted to grippingly engage at least oneaxially adjacent baffle plate whereby said gripping engagement iseffective to position said baffle plate both axially and rotationallywith respect to said adjacent baffle plates and to restrain relativeaxial and rotational movement between said bafile plates.

2. A baffle as in claim 1 in which said positioning means includesanother end adapted to grippingly engage an axially adjacent baffleplate disposed on another side of said bafi'le plate.

3. A baffle as in claim 1 in which one end of said positioning meansdefines an axially extending male connector.

4. A baffle as in claim 1 in which one end of said positioning meansdefines an axially inwardly extending socket connectron.

5. A baffle as in claim 1 in which said positioning means extends fromboth sides of said baffle plate.

6. A baffle as in claim 1 in which said baffle is made of a resilientformable thermoplastic organic compound.

7. A baffle as in claim 1 in which said positioning means is made of aresilient formable thermoplastic organic compound.

8. A baffle as in claim 1 in which a plurality of positioning means areconnected to said baffle and project from at least one side of saidbaffle plates.

9. A baffle as in claim 8 in which some of said positioning meansprojecting from said one side of said baffle plate define axiallyextending male connectors and others define axially inwardly extendingsocket connections.

10. A baffle as in claim 8 in which all of said positioning meansprojecting from said one side of said baffle plate define axiallyextending male connections.

11. A baffle as in claim 8 in which all of said positioning meansprojecting from said one side of said baffle plate define axiallyinwardly extending socket connections.

12. A shell and tube heat exchanger comprising a hollow shell; heatexchange tube means disposed within said shell; means for passing afirst heat exchange fluid inside and through said tube means; means forpassing a second heat exchange fluid into and through said shell aroundsaid tube means in heat exchange relation with said tube means; aplurality of axially spaced cross-flow baffles arranged within saidshell to provide a tortuous path for said second heat exchange fluid,each of said baffles including a plate member having axially opposedfront and rear surfaces and defining a plurality of apertures throughwhich said tube means extend; positioning means formed as an integralpart of said plate member projecting from at least one side of saidplate member, each of said positioning means having at least one endgrippingly engaged with an axially adjacent baffle plate such thatadjacent baffle plates are relatively fixed both axially androtationally with respect to said other bafi'le plates.

13. A shell and tube heat exchanger as in claim 12 in which saidpositioning means includes another end adapted to grippingly engage anaxially adjacent baffle plate disposed on another side of said baffleplate.

14. A shell and tube heat exchanger as in claim 12 in which one end ofsaid positioning means defines an axially extending male connector.

15. A shell and tube heat exchanger as in claim 12 in which one end ofsaid positioning means defines an axially inwardly extending socketconnection.

16. A shell and tube heat exchanger as in claim 12 including extensionsadapted to be disposed between adjacent bafile plates, each end of saidextensions adapted to grippingly engage said positioning means of saidadjacent bafile plates.

17. A shell and tube heat exchanger as in claim 12 in which saidpositioning means extends from both sides of said baffle late. p 18. Ashell and tube heat exchanger as in claim 12 in which said baffle ismade of a resilient formable thermoplastic organic compound.

19. A shell and tube heat exchanger as in claim 12 in which saidpositioning means is made of a resilient forrnable thermoplasticcompound.

20. A shell and tube heat exchanger as in claim 12 in which a pluralityof positioning means are connected to each of said bafile plates andproject from at least one side of said baffle lates. p 21. A shell andtube heat exchanger as in claim in which some of said positioning meansprojecting from said one side of said baffle plate define axiallyextending male connectors and others define axially inwardly extendingsocket connectrons.

22. A shell and tube heat exchanger as in claim 20 in which all of saidpositioning means projecting from said one side of said baffle platedefine axially extending male connections.

23. A shell and tube heat exchanger as in claim 20 in which all of saidpositioning means define axially inwardly extending socket connections.

24. A method of assembling an element of a heat exchanger of the tubeand shell type employing self-positioning baflle plates which define aplurality of apertures and which include positioning means formed as anintegal part of said bafflc plates and projecting from at least one sideof said bafile plates, said positioning means having at least one endadapted to grippingly engage an adjacent axially disposed baffle plate,the ste s of the method comprising: forming a tube cage by connec 'ng aplurality of said bafile plates one to another by grippingly joiningsaid positioning means of adjacent baffle plates such that the aperturesof each baflle plate are substantially axially aligned and such that thebaffles are alternately arranged to provide a tortuous path for a firstheat exchange fluid; inserting a plurality of heat exchange tubesaxially through the apertures of said bafile plate of said tube cage;inserting an assembled tube cage into a shell member; positioning a tubeplate at each end of the tube cage; sealing said heat exchange tubes tosaid tube plates; sealing said tube plates to said shell.

25. A method of assembling a heat exchanger of the tube and shell typewhich includes a shell, heat exchange tube means, a pair of tube plates,a pair of headers, and which employes self-positioning baffle plateswhich define a plurality of apertures and which include positioningmeans formed as an integral part of said baffle plates and projectingfrom at least one side of said baffle plates, said positioning meanshaving at least one end adapted to grippingly engage an adjacent axiallydisposed baffle plate, the steps of the method comprising: forming atube cage by connecting a plurality of said baffle plates one to anotherby connecting said positioning means of adjacent bafile plates such thatthe apertures of each baffle plate are substantially axially aligned andsuch that the baffles are alternately arranged to provide a tortuouspath for a first heat exchange fluid; inserting a plurality of heatexchange tubes axially through the apertures of said baffle plates ofsaid tube cage; inserting an assembled tube cage into a shell member;positioning a tube plate at each end of the tube cage; sealing said heatexchange tubes to said tube plates; sealing said tube plates to saidshell; sealing said headers to said tube plates.

26. A method of assembling a tube cage for a heat exchanger of the tubeand shell type which employs self-positioning bafile plates defining aplurality of apertures and includes positioning means fonned as anintegral part of said baffle plates and projecting from at least oneside of said baffle plates, said positioning means having at least oneend adapted to grippingly engage the adjacent baffle plate, the steps ofthe method comprising: joining a first baffle plate to a second baffleplate by grippingly engaging said positioning means of said first baffleplate to said second baffle plate such that said apertures of eachbaffle plate are substantially axially aligned and such that said bafileplates are alternately arranged to provide a tortuous path for a firstheat exchange fluid and such that said joined baffle plates arerestrained against either axial or rotational movement with respect toeach other; connecting additional bafile plates in a like manner bygrippingly engaging the positioning means of one baffle plate to saidnext adjacent baffle plate such that the apertures of all said bafllesare substantially axially aligned and such that said baffles arealternately arranged to provide a tortuous path for a first heatexchange fluid.

1. A baffle for a shell and tube heat exchanger having tubes and ahollow shell, said baffle adapted to be disposed in said shell andcomprising a plate member having axially opposed front and rear surfacesand defining a plurality of apertures; positioning means formed as anintegral part of said plate member and projecting from at least one ofsaid fRont or rear surfaces of said plate member, said positioning meanshaving at least one end adapted to grippingly engage at least oneaxially adjacent baffle plate whereby said gripping engagement iseffective to position said baffle plate both axially and rotationallywith respect to said adjacent baffle plates and to restrain relativeaxial and rotational movement between said baffle plates.
 2. A baffle asin claim 1 in which said positioning means includes another end adaptedto grippingly engage an axially adjacent baffle plate disposed onanother side of said baffle plate.
 3. A baffle as in claim 1 in whichone end of said positioning means defines an axially extending maleconnector.
 4. A baffle as in claim 1 in which one end of saidpositioning means defines an axially inwardly extending socketconnection.
 5. A baffle as in claim 1 in which said positioning meansextends from both sides of said baffle plate.
 6. A baffle as in claim 1in which said baffle is made of a resilient formable thermoplasticorganic compound.
 7. A baffle as in claim 1 in which said positioningmeans is made of a resilient formable thermoplastic organic compound. 8.A baffle as in claim 1 in which a plurality of positioning means areconnected to said baffle and project from at least one side of saidbaffle plates.
 9. A baffle as in claim 8 in which some of saidpositioning means projecting from said one side of said baffle platedefine axially extending male connectors and others define axiallyinwardly extending socket connections.
 10. A baffle as in claim 8 inwhich all of said positioning means projecting from said one side ofsaid baffle plate define axially extending male connections.
 11. Abaffle as in claim 8 in which all of said positioning means projectingfrom said one side of said baffle plate define axially inwardlyextending socket connections.
 12. A shell and tube heat exchangercomprising a hollow shell; heat exchange tube means disposed within saidshell; means for passing a first heat exchange fluid inside and throughsaid tube means; means for passing a second heat exchange fluid into andthrough said shell around said tube means in heat exchange relation withsaid tube means; a plurality of axially spaced cross-flow bafflesarranged within said shell to provide a tortuous path for said secondheat exchange fluid, each of said baffles including a plate memberhaving axially opposed front and rear surfaces and defining a pluralityof apertures through which said tube means extend; positioning meansformed as an integral part of said plate member projecting from at leastone side of said plate member, each of said positioning means having atleast one end grippingly engaged with an axially adjacent baffle platesuch that adjacent baffle plates are relatively fixed both axially androtationally with respect to said other baffle plates.
 13. A shell andtube heat exchanger as in claim 12 in which said positioning meansincludes another end adapted to grippingly engage an axially adjacentbaffle plate disposed on another side of said baffle plate.
 14. A shelland tube heat exchanger as in claim 12 in which one end of saidpositioning means defines an axially extending male connector.
 15. Ashell and tube heat exchanger as in claim 12 in which one end of saidpositioning means defines an axially inwardly extending socketconnection.
 16. A shell and tube heat exchanger as in claim 12 includingextensions adapted to be disposed between adjacent baffle plates, eachend of said extensions adapted to grippingly engage said positioningmeans of said adjacent baffle plates.
 17. A shell and tube heatexchanger as in claim 12 in which said positioning means extends fromboth sides of said baffle plate.
 18. A shell and tube heat exchanger asin claim 12 in which said baffle is made of a resilient formablethermoplastic organic compound.
 19. A shell and tube heat exchanger asin claim 12 in which said positioning means is made Of a resilientformable thermoplastic compound.
 20. A shell and tube heat exchanger asin claim 12 in which a plurality of positioning means are connected toeach of said baffle plates and project from at least one side of saidbaffle plates.
 21. A shell and tube heat exchanger as in claim 20 inwhich some of said positioning means projecting from said one side ofsaid baffle plate define axially extending male connectors and othersdefine axially inwardly extending socket connections.
 22. A shell andtube heat exchanger as in claim 20 in which all of said positioningmeans projecting from said one side of said baffle plate define axiallyextending male connections.
 23. A shell and tube heat exchanger as inclaim 20 in which all of said positioning means define axially inwardlyextending socket connections.
 24. A method of assembling an element of aheat exchanger of the tube and shell type employing self-positioningbaffle plates which define a plurality of apertures and which includepositioning means formed as an integral part of said baffle plates andprojecting from at least one side of said baffle plates, saidpositioning means having at least one end adapted to grippingly engagean adjacent axially disposed baffle plate, the steps of the methodcomprising: forming a tube cage by connecting a plurality of said baffleplates one to another by grippingly joining said positioning means ofadjacent baffle plates such that the apertures of each baffle plate aresubstantially axially aligned and such that the baffles are alternatelyarranged to provide a tortuous path for a first heat exchange fluid;inserting a plurality of heat exchange tubes axially through theapertures of said baffle plate of said tube cage; inserting an assembledtube cage into a shell member; positioning a tube plate at each end ofthe tube cage; sealing said heat exchange tubes to said tube plates;sealing said tube plates to said shell.
 25. A method of assembling aheat exchanger of the tube and shell type which includes a shell, heatexchange tube means, a pair of tube plates, a pair of headers, and whichemployes self-positioning baffle plates which define a plurality ofapertures and which include positioning means formed as an integral partof said baffle plates and projecting from at least one side of saidbaffle plates, said positioning means having at least one end adapted togrippingly engage an adjacent axially disposed baffle plate, the stepsof the method comprising: forming a tube cage by connecting a pluralityof said baffle plates one to another by connecting said positioningmeans of adjacent baffle plates such that the apertures of each baffleplate are substantially axially aligned and such that the baffles arealternately arranged to provide a tortuous path for a first heatexchange fluid; inserting a plurality of heat exchange tubes axiallythrough the apertures of said baffle plates of said tube cage; insertingan assembled tube cage into a shell member; positioning a tube plate ateach end of the tube cage; sealing said heat exchange tubes to said tubeplates; sealing said tube plates to said shell; sealing said headers tosaid tube plates.
 26. A method of assembling a tube cage for a heatexchanger of the tube and shell type which employs self-positioningbaffle plates defining a plurality of apertures and includes positioningmeans formed as an integral part of said baffle plates and projectingfrom at least one side of said baffle plates, said positioning meanshaving at least one end adapted to grippingly engage the adjacent baffleplate, the steps of the method comprising: joining a first baffle plateto a second baffle plate by grippingly engaging said positioning meansof said first baffle plate to said second baffle plate such that saidapertures of each baffle plate are substantially axially aligned andsuch that said baffle plates are alternately arranged to provide atortuous path for a first heat exchange fluid and such that said joinedbaffle plAtes are restrained against either axial or rotational movementwith respect to each other; connecting additional baffle plates in alike manner by grippingly engaging the positioning means of one baffleplate to said next adjacent baffle plate such that the apertures of allsaid baffles are substantially axially aligned and such that saidbaffles are alternately arranged to provide a tortuous path for a firstheat exchange fluid.